If you're having trouble locating your Joy-Con's Nintendo has added a feature to help you find them. The latest firmware update for the Nintendo Switch will allow players to search for missing Joy-Con's by allowing players to activate their vibrate function from the tablet. That's the kind of feature that should've been implemented in consoles ages ago! Personally, I don't take my joy-con controllers off the tablet all that often, but I appreciate that if I ever lose a controller, I have a better shot at finding it now. 

Source: GameSpot